Hi, guys,
Recently, I encountered an IO hang problem in occasion which I cannot reproduce it now.
I analyzed this problem carefully, the critical stack is as
following:
After reading the codes in linux-aio.c(see ioq_submit() function), I found two situations could lead us here.
1) no AIOs are in flight(s->ioq.in_flight is 0) and another
call to io_submit returns -EAGAIN
2) no AIOs are in flight(s->ioq.in_flight is 0) and
s->io_q.pending IOs reach to MAX_EVENTS at once
In both the two situations above, the do{...}while loop breaks out and set s->io_q.blocked true.
After that, AIO completion callback will never be called, ioq_submit() either, all pended requests will hang.
Is there a proper way we can fix this while do not affect(stuck) the guest ?
Hope for a reply, thanks.
Sochin.